Fluidization process



2,962,447 FLUIDIZATION PROCESS William A. Kelly, Teaneck, N.J., assignor to Lever Brothers Company, New York, N.Y., a corporation of Maine No Drawing. Filed May 1,1958, Ser. No. 732,119

3'Claims. (Cl. 252-117) This invention is concerned with a novel process for obtaining sodium tallow methyl taurate in a fluid condition. In particular, it is concerned with a process for fluidizing sodium tallow methyl taurate by adjustment of the water and soap contents to within certain ranges.

Sodium tallow methyl taurate is used industrially as a detergent. It is most frequently used in the form of mixtures with other materials, and it is therefore often desirable that the sodium tallow methyl taurate be obtained in a fluid condition so that it can be blended homogeneously with other materials. In addition, it is often desirable to fluidize the material so that it can be conveniently handled during factory operations, for example, in order that it can be moved from place to place by flow through a pipe and in order that it can be pumped.

The name sodium tallow methyl taurate is that generally used to describe the sodium salt of fatty acyl methyl taurate where the fatty acyl groups are of the type derivable from the fatty acids of tallow. The material is prepared by a condensation reaction between N-methyl taurine and fatty acid from tallow. The product of such a reaction shows a typical analysis of about 54% sodium tallow methyl taurate, about 32% free fatty acids, and about 14% miscellaneous impurities including from about 2 to 8% soap from the reaction. The product must be heated to about 250 F. in order to be liquefied. At 250 F., however, the material darkens rapidly when exposed to air. When the material is cooled to below 250 F., it becomes extremely viscous, and pumping and storing in the liquid form are impossible.

At room temperature, the sodium tallow methyl taurate reaction mixture is a hard, somewhat sticky solid. When it is flaked on a chill roll and stored in bins or drums, the flakes tend to compact and form large lumps. Flakes also tend to lump when mixed with soap in a crutcher, and the flakes are diflicult to melt into a homogeneous mass during crutching.

It has now been found that by proper adjustment of the water and soap content it is possible to obtain the sodium tallow methyl taurate in a fluidized condition. Since the material in the fluidized state behaves as a non- Newtonain liquid, the actual measurement of viscosity is difiicult to define. The fluidized material, however, is capable of flowing through a four inch pipe at tempera tures as low as about 150 F. Furthermore, it may be pumped at such temperatures, and it may be kept in a homogeneous fluid state for long periods of time without the necessity for mixing. Even at room temperature, the fluidized mixture still has the consistency and flow characteristics of heavy grease, as contrasted with a completely solid material that would result if the process of the invention were not used.

In carrying out the process of the present invention, the soap content of the material is adjusted so that the amount of soap constitutes about 2 to 18% by Weight of the total dry components, and water is admixed. The water content of the fluidized mixtures generally ranges from about 20% to about 30%. When either an insuflicient atent O 2,962,447 Patented Nov; 29, 1960 or an excessive amount of water is used, proper fluidization is not obtained, and the mixture becomes extremely viscous and diflicult to pump or to handle by means of a gravity flow.

It is important that the soap concentration be adjusted to Within the proper range. When between about 2% and about 5% of soap is present, the mixture will not remain homogeneous, and the use of a mixing device is necessary. Most surprisingly, if the soap content is above about 18%, viscosity is greatly increased, and the mix- 1 ture becomes too viscous for practical purposes.

The proper water content is to some extent a function of the soap content. As the level of the soap content is increased within the range of from about 2 to 18%, both the upper and the lower limit of desirable water content become lower, and the range between them becomes narrower. At a soap content of about 5%, about 22% water is required for fluidization, and the water content may go as high as about 30%. When the soap content is about 8%, the mixture will be fluidized by about 21% Water, but will become too viscous when the water content is increased above about 29%. At a soap content of about 12%, the Water content should be kept below about 26%, but as little as 20% water will serve to make the mixture fluid.

There is some evidence to indicate that the preferred rang of water content may vary somewhat depending upon the ratio of cis and trans isomers in the fatty acids from which the sodium tallow methyl taurate has been prepared, and that as the amount of trans isomer increases, the desirable lower level of water content tends to be raised somewhat, and the desirable upper level of water content tends to be lowered somewhat.

It is thus seen that the optimum conditions for fluidization of any particular batch of sodium tallow methyl taurate will vary within the ranges for soap and water content given above. It may, however, be said that results approaching the optimum will generally be obtained with a water content of approximately 25% and soap content before the addition of water of approximately 8%. It is probable that a water concentration of about 25 and a soap concentration of about 8% represent an area near the center of an area which would be obtained on a graph by plotting the permissible soap content on the ordinate and the permissible water content on the abscissa. The area obtained by such a graphic plotting is probably irregular in shape, being somewhat narrower on the top than at the base and resembling a trapezoid the top of which is closer to the ordinate than is the base.

In carrying out the process of the invention, the sodium tallow methyl taurate is heated to above 260 F., preferably to about 310 F. The water content may be adjusted by mixing separate streams of molten taurate and water. When the soap content of the taurate is not already at the desired level, it may be adjusted by means of soap or caustic soda added to the water before proportioning, or it may be adjusted prior to the mixing with water. The proportioning pumps direct the sodium methyl taurate at about 310 F. and water or aqueous alkali at about 70 F. into the suction side of a centrifugal pump which is fitted with a bypass for recirculation. The sodium tallow methyl taurate and water or aqueous alkali are mixed in a centrifugal pump and formed into a fluid mass at a temperature of -210" F.

What is claimed is:

1. A process for fluidizing the reaction product obtained when sodium tallow methyl taurate has been prepared by the reaction between N-methyl taurine and tallow fatty acid, comprising mixing the molten reaction product with from about 2% to about 18% of watersoluble soap, based on the weight of the total dry components, and water in the proportion of about 20 to 30 parts by weight for each 80 to 70 parts by weight of dry components, the temperature of the sodium tallow methyl taurate reaction product initially being above about 260 F. and the temperature of the water being such that the mixture has a temperature of above 150 F.

2. A process as claimed in claim lin which the temperature of the sodium tallow methyl taurate reaction product is about 310 F. and the temperature of the water is such that the mixture has a temperature of about 190 F.

3. A process for fluidizing the reaction product obtained when sodium tallow methyl taurate has been prepared by the reaction between N-methyl taurine and tallow fatty acid, comprising adjusting the soap content of the reaction product to about 8% ofwater-soluble References Cited in the file of this patent UNITED STATES PATENTS Guenther et a1 Oct. 23, 1933 Sundberg Oct. 21, 1958 OTHER REFERENCES Ind. and Eng. Chem, 42, pp. 1626-38, September 1950, article by Kastens et a1.

Chemical Week, Jan. 9, 1954, page 70, Stafl report. 

1. A PROCESS FOR FLUIDIZING THE REACTION PRODUCT OBTAINED WHEN SODIUM TALLOW METHYL TAURATE HAS BEEN PREPARED BY THE REACTION BETWEEN N-METHYL TAURINE AND TALLOW FATTY ACID, COMPRISING MIXING THE MOLTEN REACTION PRODUCT WITH FROM ABOUT 2% TO ABOUT 18% OF WATERSOLUBLE SOAP, BASED ON THE WEIGHT OF THE TOTAL DRY COMPONENTS, AND WATER IN THE PROPORTION OF ABOUT 20 TO 30 PARTS BY WEIGHT FOR EACH 80 TO 70 PARTS BY WEIGHT OF DRY COMPONENTS, THE TEMPERATURE OF THE SODIUM TALLOW METHYL TAURATE REACTION PRODUCT INITIALLY BEING ABOVE ABOUT 260* F. AND THE TEMPERATURE OF THE WATER BEING SUCH THAT THE MIXTURE HAS A TEMPERATURE OF ABOVE 150*F. 